How to choose the number of lumens of a projector?
Lumens have become a somewhat misunderstood specification, much like watts in audio. Sure, lumens count matters when choosing a projector, but it’s a more complex and technical question. For now, let’s clarify the most important thing:
Lumens (lm) is the SI-based unit that measures luminous flux (the electromagnetic waves that the human eye can see). ANSI lumens is a unit, defined by the American National Standards Institute (ANSI), that measures the total amount of light delivered by a projector. Not just the light output of the lamp. An ANSI lumen measures the brightest white light the projector can produce.
But one thing is the light emitted and another is the light perceived by the eye when this light (coming from the projector) is reflected on a screen. The latter depends on the brightness of the projector, the size of the screen, the gain of the screen and the ambient light. All this constitutes a new measurement called Foot-Lambert (ftL) which is the unit of measurement used by the film industry to specify the amount of light that should be reflected on the cinema screen in an area of 1 foot x 1 foot. The specification for a commercial cinema (in the dark) is between 16 and 18 piL. Today, with average ambient light, the perceived brightness is between 40 and 59 piL.
So we need projectors for these applications:
- Dark Home Theater (100-150 inches): 1,000-2,500 lumens
- Home theater with ambient light (100-150 inches): 2,500-4,000 lumens
- Small meeting room (100-160 inches): 3,000-5,000 lumens
- Large conference room (150-200 inches): 5,000-8,000 lumens
- Classroom (100-160 inches): 4,000 to 6,000 lumens
- Gyms: (150-200 inches): 6,000-10,000 lumens
- Museum (130-180 inches): 4,000 to 8,000 lumens
- Large auditoriums (150-250 inches): 7,000 to 11,000 lumens
- Churches (140-250 inches): 6,000 to 15,000 lumens
